1. Field of the Invention
The present invention relates to a recording thin film magnetic head used as, for example, a flying magnetic head, or the like, and particularly, to a thin film magnetic head in which the magnetic path can be shortened to decrease inductance, and withstand voltage between a lower core layer and a coil layer can be improved, and a manufacturing method therefor.
2. Description of the Related Art
FIG. 36 is a partial longitudinal sectional view showing the structure of a conventional thin film magnetic head (inductive head).
In FIG. 36, reference numeral 1 denotes a lower core layer made of a magnetic material such as permalloy, or the like, and a recording region 12 is formed on the lower core layer 1 near the surface facing a recording medium.
The recording region 12 comprises, for example, a gap layer 4 and an upper pole layer 4 made of a magnetic material.
In addition, a coil layer 5 is formed on the rear region of the upper core layer 1, which is behind the recording region in the height direction (the Y direction shown in FIG. 36).
Furthermore, the pitch intervals of a conductor of the coil layer 5 is filled with an insulation layer 11, and an insulation layer 7 made of an organic material or the like is formed on the coil layer 5 and the insulation layer 11.
As shown in FIG. 36, an upper core layer 8 made of permalloy or the like is formed in the region from the recording region 12 to the insulation layer 7 so that the front end 8a of the upper core layer 8 is magnetically connected to the upper top pole layer 4, and the base end 8b is magnetically connected to the lower core layer 1. As shown in FIG. 36, the front end of the upper core layer 8 may be formed at a position shifted backward from the surface facing the recording medium, or exposed from the surface facing the recording medium.
This thin film magnetic head has a construction in which the coil layer 5 is provided behind the recording region 12 in the height direction so that the magnetic path ranging from the upper core layer 8 to the lower core layer 1 can be shortened to decrease inductance, thereby making adaptable to a higher recording density in future.
As shown in FIG. 36, an insulation underlying layer 9 is formed between the coil layer 5 and the lower core layer 1 to maintain electric insulation between the coil layer 5 and the lower core layer 1.
However, the thin film magnetic head shown in FIG. 36 causes the following problems.
Since the coil layer 5 must be formed behind the recording region 12 in the height direction (the Y direction shown in FIG. 36), the insulation underlying layer 9 must be thinly formed between the coil layer 5 and the lower core layer 1, thereby failing to sufficiently maintain withstand voltage between the coil layer 5 and the lower core layer 1.
The insulation underlying layer 9 is thinly formed by sputtering using an inorganic insulating material, for example, such as Al2O3, or the like.
However, in depositing the thin film by sputtering, the insulation underlying layer 9 is easily contaminated with dust particles (impurities) present in a sputtering apparatus to decrease the withstand voltage of the insulation underlying layer 9.
Also, in forming the thin insulation underlying layer 9 by sputtering, pinholes or the like easily occur in the insulation underlying layer 9, thereby further decreasing the withstand voltage.
Conversely, when the thick insulation underlying layer 9 is formed to a thickness sufficient to secure the withstand voltage between the lower core layer 1 and the coil layer 5, and the coil layer 5 is formed so that the upper surfaces of the coil layer 5 and the recording region 12 lie in substantially the same plane, as shown in FIG. 36, the coil layer 5 is thinned, and thus the width dimension T1 of the coil layer 5 must be increased from the viewpoint of decreasing the coil resistance value. Therefore, the magnetic path ranging from the upper core layer 8 to the lower core layer 1 is lengthened to increase inductance, thereby failing to manufacture a thin film magnetic head adaptable to a higher recording density.
Even when the thick insulation underlying layer 9 is formed, the withstand voltage of the insulation underlying layer 9 cannot be effectively improved due to the above-described contamination with dust particles during sputtering.